The present invention relates generally to the decontamination of avian shell eggs, and specifically to the reduction of microbial contaminants on both the exterior and interior of avian shell eggs through the application of gaseous ozone, carbon dioxide, pressure, heat, ultraviolet radiation, and combinations thereof.
Contamination of shell-eggs by microorganisms such as Salmonella Enteritidis constitutes a health hazard to consumers, an added liability to the food industry itself, and an extra burden on governmental agencies involved in regulation and surveillance of the food industry. The fresh egg is one of the most common vehicles for the transmission of Salmonella spp. to humans. Salmonellosis, the food transmitted disease caused by Salmonella spp., results from the consumption of either contaminated shell-eggs or manufactured products containing egg components. According to some estimates, only 1 in 20,000 raw eggs in the United States are contaminated with Salmonella Enteritidis; however, the Centers for Disease Control and Prevention (CDC) reported in 1997 a total of 300,000 cases of disease attributable to Salmonella Enteritidis (CDC, Morbid. Mortal Weekly Rep. Vol 49 (SS-1):1-72, 2000).
The primary objectives of food sanitation include reducing the levels of microorganisms in food and preventing or limiting further proliferation of microorganisms that contaminate food items. Food sanitation typically involves applying one or more established decontamination procedures to various food items.
Cleaning eggs by washing is a common practice which is required in plants operating under the Federal Grading Service. Egg washers currently used by the food industry spray the eggs with water that contains commercially available sanitizers and detergents. Thermal and chemical treatments have been developed to control or eliminate Salmonella Enteritidis in eggs; however, these methods are time consuming, uneconomical and may be only partially effective. Other known decontamination methods include the use of the following: quaternary ammonium compounds, organic acids, high temperature and high pH, gamma irradiation, short-wave ultraviolet light, and ozone.
Irradiation of certain food products with short-wave ultraviolet (UV) light has been demonstrated to be effective for inhibiting the growth of microorganisms on food surfaces, destroying airborne microorganisms and sterilizing liquids. The literature also indicates that UV-light effectively reduces the contamination of shell-eggs by aerobic bacteria, yeasts and molds, and Salmonella Typhimurium. Additionally, heat treatment of shell eggs has been utilized to sanitize the surface and to eliminate internal Salmonella Enteritidis in eggs.
Despite the methodologies discussed above, there currently are no low-temperature treatments capable of effectively sanitizing eggs. Low temperatures are known to preserve the quality and safety of shell-eggs during production, storage, transportation and retail. Maintaining the shell eggs at low temperatures may significantly reduce the incidence of Salmonella Enteritidis egg-related illnesses. Thus, there is a need for low-temperature treatments for effectively sanitizing eggs.
These and other disadvantages of the prior art are overcome by the present invention which provides a method for reducing external contamination of shell eggs and a method for reducing internal contamination of shell eggs. Both methods utilize gaseous ozone. Reduction of induced external Salmonella Enteritidis contamination at low temperatures is achieved using gaseous ozone applied under mild pressure, alone or in combination with UV radiation. In one embodiment, reduction of internal Salmonella Enteritidis contamination of shell eggs is achieved using a combination of heat, vacuum, and gaseous ozone under mild pressure. In another embodiment, reduction of internal Salmonella Enteritidis contamination of shell eggs is achieved using a combination of heat, vacuum, and a mix of carbon dioxide and gaseous ozone.
A preferred method for treating the exterior of a contaminated, unfertilized shell egg includes the steps of placing a contaminated shell egg (which is at or below ambient or room temperature) in a sealed vessel, wherein the internal pressure of the sealed vessel is equal to atmospheric pressure, increasing the pressure inside the vessel to greater than atmospheric pressure by introducing gaseous ozone into the sealed vessel, and maintaining the shell egg in the sealed vessel for a brief period of time.
An alternate method for treating the exterior of a contaminated, unfertilized shell egg includes the steps of exposing the shell egg to ultraviolet light, transferring the contaminated shell egg in a sealed vessel, wherein the internal pressure of the sealed vessel is equal to atmospheric pressure, increasing the pressure inside the vessel to greater than atmospheric pressure by introducing gaseous ozone into the sealed vessel, and maintaining the shell egg in the sealed vessel for a brief period of time.
A preferred method for treating the interior of a contaminated, unfertilized shell egg includes the steps of placing the shell egg (which is at or below ambient temperature) in a sealed vessel, wherein the internal pressure of the sealed vessel is equal to atmospheric pressure, decreasing the pressure inside the vessel to less than atmospheric pressure, introducing gaseous carbon dioxide into the sealed vessel, introducing gaseous ozone into the sealed vessel, and maintaining the shell egg in the sealed vessel for a brief period of time.
An alternate method for treating the interior of a contaminated, unfertilized shell egg includes the steps of heating the shell egg, transferring the heated shell egg to a sealed container, wherein the internal pressure of the sealed container is equal to atmospheric pressure, decreasing the internal pressure of the sealed vessel to below atmospheric pressure, introducing gaseous ozone into the sealed vessel, and maintaining the shell egg in the sealed vessel for a brief period of time.
Another alternate method for treating the interior of a contaminated, unfertilized shell egg includes the steps of heating the shell egg, transferring the heated shell egg to a sealed container, wherein the internal pressure of the sealed container is equal to atmospheric pressure, decreasing the internal pressure of the sealed vessel to below atmospheric pressure, introducing gaseous carbon dioxide into the sealed vessel, introducing gaseous ozone into the sealed vessel, and maintaining the shell egg in the sealed vessel for a brief period of time.
Further advantages of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments.